Effects of Infusion and Decoction Mashing on Carbohydrate Structure, Fermentation Behavior, and Volatile Compound Profiles in Wheat Beer

Beer flavor depends on the composition and structural characteristics of fermentable carbohydrates generated during mashing. Although mashing strategy is known to influence wort composition, the mechanistic relationship between mashing-induced variations in carbohydrate structure and subsequent yeast metabolism and flavor formation remains poorly understood. This study aimed to compare the effects of two mashing procedures, infusion mashing (IMM) and decoction mashing (DMM), on carbohydrate structure, fermentation behavior, and flavor attributes of wheat beer. The physicochemical properties were analyzed using standard methods; organic acids, amino acids, and volatile compounds were analyzed using chromatographic techniques combined with multivariate analysis. Instrumental aroma and taste characteristics were further assessed using electronic nose and electronic tongue systems. Compared with IMM, DMM wort contained numerically higher proportions of low-degree-of-polymerization carbohydrates and higher amino acid concentrations. These compositional differences were associated with divergent fermentation kinetics and distinct volatile and nonvolatile metabolite profiles in the finished beers. DMM was associated with higher concentrations of medium-chain fatty acid ethyl esters, whereas IMM was associated with higher concentrations of acetate esters, higher alcohols, and aldehydes, consistent with faster fermentation and enhanced amino acid catabolism. Multivariate analysis confirmed differentiation in volatile profiles and instrumental aroma characteristics between the two beers. Together, these results suggest an association of mashing strategy with variations in carbohydrate structure, fermentation behavior, and volatile compound profiles in wheat beer. These findings offer a framework for the process-level control of beer flavor.